Wavefront and topography: Keratome-induced corneal changes demonstrate that both are needed for custom ablation

PURPOSE: To examine the effects of laser in situ keratomileusis (LASIK) flap incision and healing on the shape of the cornea and the wavefront error of the eye. METHODS: Four weeks prior to bilateral LASIK, study subjects had a flap cut using a keratome in one eye. The fellow eye remained untouched as a control. Corneal topography and wavefront errors were measured at 1 day, 1, and 4 weeks after the flap was created. After 4 weeks, the flap was lifted and LASIK was performed. The control eye also had LASIK at this time. RESULTS: Differences in corneal shape and wavefront error consistent with a mild hyperopic shift were seen as a result of the keratome incision. CONCLUSION: Cutting the flap in LASIK causes subtle changes to corneal shape and the optics of the eye that may affect customized treatments. Additional work is needed to quantify these changes so that their effect can be incorporated into future treatments.